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Datums Page Page 1 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
To reach the tidal bench marks from the Deadhorse Airport, proceed SW (left) on
Deadhorse Road fronting the airport for 0.2 km (0.1 mi) to the first
intersection, then turn north (right) onto Airport Road for 0.3 km (0.2 mi) to a
"Y" intersection at Lake Colleen, head NW (left) for 3.1 km (1.9 mi) to the West
Check Point on Spine Rd., then head 5.8 km (3.6 mi) NW on Spine Rd. to the
intersection with Oxbow Rd., then turn north (right) for 6.6 km (4.1 mi) on
Oxbow Rd. to its termination on an unnamed coastal road, then turn NW (left) for
11.9 km (6.9 mi) on the unnamed road to the start of the West Dock causeway at
McIntyre Point, then head NNE (right) for 4.2 km (2.6 mi) to the Seawater
Treatment Plant (STP) operated by British Petroleum (BP) at the end of the
causeway. The bench marks are located along the southern end of the STP and the
east side of the causeway. The tide station is located in the west reservoir
room of the STP.
T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING:
DESIGNATION: 949 7645 CELL 4B
ALIAS: CELL 4B, NO STAMPING 1
MONUMENTATION: See descriptive text VM#: 4597
AGENCY: ARCO Oil Company IDB PID#:
SETTING CLASSIFICATION: Sheet pile OPUS PID:
LATITUDE: 70° 24.7' N ( 70.41106) LONGITUDE: 148° 32.0' W (-148.53256)
The primary bench mark is the center of a triangular shaped steel connecting pin
that joins the 6th and 7th sheet pile cells at the SW corner of the British
Petroleum (BP) Seawater Treatment Plant (STP), 27.88 m (91.5 ft) SW of the
bottom of the metal stairs at the SW corner of the STP, 11.09 m (36.4 ft) SW of
bench mark 949 7645 CELL 5B, and 9.05 m (29.7 ft) NE of the SW corner of the
1.24 m (4.1 ft) high safety railing where the railing changes from a north/south
orientation to a NE/SW orientation.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 949 7645 CELL 5B
ALIAS: CELL 5B, NO STAMPING 2
MONUMENTATION: See descriptive text VM#: 4599
AGENCY: ARCO Oil Company IDB PID#:
SETTING CLASSIFICATION: Sheet pile OPUS PID:
LATITUDE: 70° 24.7' N ( 70.41122) LONGITUDE: 148° 31.9' W (-148.53228)
The bench mark is the center of a triangular shaped steel connecting pin that
joins the 3rd and 4th sheet pile cells at the SW corner of the British Petroleum
(BP) Seawater Treatment Plant (STP), 16.92 m (55.5 ft) SW of the bottom of the
metal stairs at the SW corner of the STP, 11.20 m (36.7 ft) SW of bench mark 949
7645 CELL 6B, 11.09 m (36.4 ft) NE of bench mark 4B, and 3.32 m (10.9 ft) SW of
the SW side of the gate leading to the ladder that provides access to the
seasonal small boat dock on the south side of the STP.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 949 7645 CELL 6B
ALIAS: CELL 6B, NO STAMPING 3
MONUMENTATION: See descriptive text VM#: 4600
AGENCY: ARCO Oil Company IDB PID#:
SETTING CLASSIFICATION: Sheet pile OPUS PID:
LATITUDE: 70° 24.7' N ( 70.41133) LONGITUDE: 148° 31.9' W (-148.53214)
The bench mark is the center of a triangular shaped steel connecting pin that
joins two sheet pile cells at the SW corner of the British Petroleum (BP)
Seawater Treatment Plant (STP), 11.20 m (36.7 ft) NE of bench mark 949 7645 CELL
5B, 9.14 m (30.0 ft) SW of the west wall of the STP (distance measured along the
safety rail), 8.00 m (26.2 ft) NE of the SW side of the gate leading to the
ladder that provides access to the seasonal small boat dock on the south side of
the STP, and 6.40 m (21.0 ft) south of the base of the metal stairs at the SW
corner of the STP.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 949 7645 SW RAIL
ALIAS: SW RAIL, NO STAMPING 4
MONUMENTATION: See descriptive text VM#: 4601
AGENCY: ARCO Oil Company IDB PID#:
SETTING CLASSIFICATION: Metal railing support OPUS PID:
LATITUDE: 70° 24.0' N ( 70.40000) LONGITUDE: 148° 31.6' W (-148.52700)
The bench mark is the corner of a 0.11 m (0.4 ft) diameter grey metal railing
inside of the STP, supporting four unused intake doors for BP's Seawater
Treatment Plant (STP) and marked with two purple stickers that have "SW Rail"
written on them, 4.52 m (14.8 ft) NE of the center of Door 18, 4.45 m (14.6 ft)
north of the south wall, 4.07 m (13.4 ft) east of the west wall, 2.46 m (8.1 ft)
NE of the Aquatrak well, and 1.02 m (3.3 ft) above the deck.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 949 7645 STEEL PIN
ALIAS: STEEL PIN, NO STAMPING 5
MONUMENTATION: Metal Rod VM#: 4602
AGENCY: ARCO Oil Company IDB PID#:
SETTING CLASSIFICATION: Sheet pile OPUS PID:
LATITUDE: 70° 24.0' N ( 70.40000) LONGITUDE: 148° 31.6' W (-148.52700)
The bench mark is the head of a 3/4-inch diameter steel pin that has been driven
between the 4th and 5th cells from the SE corner of the STP, 18.26 m (59.9 ft)
SE of bench mark 949 7645 TBM DEADMAN, 13 m (43 ft) NW of the top of the access
ramp to the seasonal dock, 1.64 m (5.4 ft) north of the safety rail, and
projects 3 cm (1 in) above the gravel pad.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 949 7645 BOLLARD ARM
ALIAS: BOLLARD ARM [1992], NO STAMPING
10
MONUMENTATION: See descriptive text VM#: 12620
AGENCY: ARCO Oil Company IDB PID#:
SETTING CLASSIFICATION: Steel bollard OPUS PID#: BBFH06
LATITUDE: 70° 24.8' N ( 70.41325) LONGITUDE: 148° 31.9' W (-148.53219)
The bench mark is the top of the west end of the NW arm of a 24-inch steel
bollard located in the NW corner of the gravel pad surrounding BP's Seawater
Treatment Plant (STP), 77.1 m (252.9 ft) NW of the north end of the bull rail in
the parking lot on the west side of the STP, 46.5 m (152.6 ft) NW of the NW
corner of the STP, 16 m (52 ft) south of the north edge of the gravel-sand bag
interface, and 0.5 m (1.6 ft) above the gravel pad.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 949 7645 NE STP
ALIAS: NE STP, NO STAMPING 12
MONUMENTATION: See descriptive text VM#: 13867
AGENCY: Arco Oil Company IDB PID#:
SETTING CLASSIFICATION: Steel bollard eye OPUS PID:
LATITUDE: 70° 24.8' N ( 70.41278) LONGITUDE: 148° 31.8' W (-148.53033)
The bench mark is a high point on an eye directly south of the double bollard at
the NE corner of BP's Seawater Treatment Plant (STP), 6.3 m (21 ft) SE of the
bottom of the metal stairs, 4.1 m (13 ft) south of the north edge of the barge,
0.6 m (2 ft) west of the east edge of the barge, 0.3 m (1 ft) south of the
southern bollard post, and 0.20 m (0.7 ft) above the barge.
BENCH MARK STAMPING:
DESIGNATION: 945 7645 SW STP
MONUMENTATION: See descriptive text VM#: 21727
AGENCY: IDB PID#:
SETTING CLASSIFICATION: Steel bollard eye OPUS PID:
LATITUDE: 70° 24.7' N ( 70.41111) LONGITUDE: 148° 31.8' W (-148.53083)
The bench mark is the high point on the steel bollard eye 0.5 m (1.6 ft) N of
the double bollard on the deck level at the SW corner of BP seawater treatment
plant, 2.8 m (9.2 ft) S of the SW corner of the STP deck house, 0.5 m (1.6 ft)
E of the W edge of the barge, and 20 cm (8 inches) higher than the barge.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 9 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 949 7645 WINDSOCK RESET 2016
MONUMENTATION: See descriptive text VM#: 22108
AGENCY: National Ocena Service IDB PID#:
SETTING CLASSIFICATION: Windsock tower anchor OPUS PID:
LATITUDE: 70° 24.4' N ( 70.40583) LONGITUDE: 148° 31.7' W (-148.52897)
The bench mark is the high point on a 5-inch (13 cm) diameter auger bit which is
the NW most anchor for the windsock tower of the old state of Alaska tide
station, 0.56 km (0.35 mi) SE of BP's seawater treatment plant, 23 m (75.5 ft)
NE of the center line of the road leading to the plant, 4.50 m (14.8 ft) NW of
the windsock tower, 2.25 m (7.4 ft) NW of the NW corner of the platform for the
old tide house and 0.6 m (2.0 ft) higher than the gravel.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 10 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
T I D A L D A T U M S
Tidal datums at PRUDHOE BAY based on:
LENGTH OF SERIES: 16 YEARS
TIME PERIOD: 12/93-11/04, 3/06-2/08,7/08-6/11
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (08/11/2000) = 1.464
MEAN HIGHER HIGH WATER MHHW = 0.214
MEAN HIGH WATER MHW = 0.181
MEAN SEA LEVEL MSL = 0.106
MEAN TIDE LEVEL MTL = 0.103
MEAN LOW WATER MLW = 0.025
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (03/04/2013) = -1.044
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
949 7645 CELL 4B 5.466 5.285
949 7645 CELL 5B 5.413 5.232
949 7645 CELL 6B 5.463 5.282
949 7645 SW RAIL 4.505 4.324
949 7645 STEEL PIN 5.618 5.437
949 7645 BOLLARD ARM 8.789 8.608
949 7645 NE STP 9.057 8.876
945 7645 SW STP 9.076 8.895
949 7645 WINDSOCK RESET 2016 2.781 2.600
Foot Notes:
Bench mark 949 7645 WINDSOCK RESET 2016 is based on one differential leveling
connection and does not meet the quality control standards of the NOS.
Therefore, caution should be used when deriving elevations for this mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 11 of 11
Station ID: 9497645 PUBLICATION DATE: 09/20/2017
Name: PRUDHOE BAY
AK
NOAA Chart: 16061 Latitude: 70° 24.7' N ( 70.41142)
USGS Quad: BEECHEY POINT(S) B-3 Longitude: 148° 31.9' W (-148.53178)
D E F I N I T I O N S
Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal
Datum Epoch. It pertains to local mean sea level and should not be confused
with the fixed datums of North American Vertical Datum of 1988 (NAVD88).
NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum
constraint adjustment of Canadian/Mexican/United States leveling observations.
Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as
the single initial constraint. NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD29 was originally derived from a general
adjustment of the first-order leveling networks of the U.S. and Canada after
holding mean sea level observed at 26 long term tide stations as fixed.
Numerous local and wide-spread adjustments have been made since establishment in
1929. Bench mark elevations relative to NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to
local MSL and other tidal datums may not be consistent from one location to
another.
The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique
identifiers for bench marks in the tidal and geodetic databases, respectively.
Each bench mark in either database has a single, unique VM# and/or PID# assigned.
Where both VM# and PID# are indicated, both tidal and geodetic elevations are
available for the bench mark listed. The NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 elevation relationship shown in the table is derived from an average
of several bench mark elevations relative to tide station datum. As a result of
this averaging, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.